# US 10,480,406 B2 · Gas turbine cycle equipment, equipment for recovering CO2 from flue gas, and method for recovering exhaust heat from combustion flue gas

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- Number: US 10,480,406 B2
- Document ID: US10480406B2
- Status: Granted
- Kind: B2
- Application number: 15/307,183
- Filed: 2015-04-24
- Published: 2017-04-27
- Granted: 2019-11-19
- Earliest claimed: 2014-05-15
- Assignees: Mitsubishi Heavy Industries Engineering, Ltd.
- Applicants: Mitsubishi Heavy Industries, Ltd.
- Inventors: Masaki Iijima
- Web page: https://patentgrep.com/patent/US10480406B2

## CPC

- F02C 6/06: providing compressed gas (F02C6/10 takes precedence)
- B01D 53/1425: {Regeneration of liquid absorbents}
- B01D 53/1475: {Removing carbon dioxide}
- F01K 21/047: {having at least one combustion gas turbine}
- F02C 3/04: having a turbine driving a compressor (power transmission arrangements F02C7/36; control of working fluid flow F02C9/16)
- F02C 3/30: Adding water, steam or other fluids {for influencing combustion, e.g. to obtain cleaner exhaust gases (F02C7/141, F02C7/30, F01D21/00, F01K21/04, F23D11/10 take precedence)}
- F02C 3/305: {Increasing the power, speed, torque or efficiency of a gas turbine or the thrust of a turbojet engine by injecting or adding water, steam or other fluids (F01K21/04 takes precedence)}
- F02C 7/08: Heating air supply before combustion, e.g. by exhaust gases
- F02C 7/14: of fluids in the plant {, e.g. lubricant or fuel (F02C7/185 takes precedence)}
- F02C 7/1435: {by water injection}
- F22B 1/1815: {using the exhaust gases of gas-turbines}
- F28C 1/00: Direct-contact trickle coolers, e.g. cooling towers (building construction E04H5/12; enclosed spaces cooled by trickle F25; components parts of trickle coolers F28F25/00; {indirect-contact cooling towers F28B1/06})
- F28C 1/14: comprising also a non-direct contact heat exchange
- B01D 53/62: Carbon oxides
- B01D 2252/204: Amines
- B01D 2257/504: Carbon dioxide
- B01D 2258/0283: Flue gases
- F05D 2220/32: in gas turbines
- F05D 2220/60: making use of surplus or waste energy
- F05D 2220/75: equipment using fuel having a low calorific value, e.g. low BTU fuel, waste end, syngas, biomass fuel or flare gas
- F05D 2220/76: an electrical generator
- F05D 2240/35: Combustors or associated equipment
- F05D 2260/211: by intercooling, e.g. during a compression cycle
- F05D 2260/212: by water injection
- F05D 2260/213: by the provision of a heat exchanger within the cooling circuit
- F05D 2260/61: Removal of CO2
- F28C 2001/006: {Systems comprising cooling towers, e.g. for recooling a cooling medium}
- Y02C 20/40: of CO2
- Y02E 20/16: Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
- Y02E 20/32: Direct CO2 mitigation
- F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00)
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- F01K: STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES (gas-turbine or jet-propulsion plants F02; nuclear power plants, engine arrangements therein G21D)
- F22B: METHODS OF STEAM GENERATION; STEAM BOILERS
- F28C: HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA COME INTO DIRECT CONTACT WITHOUT CHEMICAL INTERACTION (safety devices in general F16P; fluid heaters having heat generating means F24H; with an intermediate heat-transfer medium coming into direct contact with heat-exchange media F28D15/00 - F28D19/00; details of heat-exchange apparatus of general application F28F)
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

By using a combustion flue gas (18) from a power turbine (16), a high-pressure secondary compressed air (12C) is subjected to heat exchange in a first heat exchange unit (19A) of an exhaust heat recovery device (19), and by using resultant heat-exchanged flue gas (18A), a low-pressure primary compressed air (12A) is subjected to heat recovery in a second heat exchange unit (19B) of a saturator (31). Then, a primary compressed air (12B) that has been subjected to heat recovery in the second heat exchange unit (19B) is introduced into a secondary air compressor (22) to increase the pressure of the air, and then the high-pressure air is subjected to heat recovery in the first heat exchange unit (19A), producing a secondary compressed air (12D). The secondary compressed air (12D) is introduced into a combustor (14) and combusted using fuel.

## Claims

### Claim 1

A method for recovering exhaust heat from combustion flue gas produced by a system, the system comprising a gas turbine having a combustor configured to combust fuel with compressed air, a power turbine configured to be driven by combustion flue gas from the combustor, and an exhaust heat recovery device configured to receive the combustion flue gas from the power turbine and recover heat energy from the combustion flue gas, wherein the gas turbine comprises a primary air compressor and a secondary air compressor, the primary air compressor being configured to compress air to produce primary compressed air, the secondary air compressor being configured to compress the primary compressed air to produce secondary compressed air, wherein the compressed air includes the primary compressed air and the secondary compressed air, wherein the exhaust heat recovery device includes a heat exchanger configured to perform indirect heat exchange between the combustion flue gas and the secondary compressed air, and a saturator provided downstream, with respect to a flow of the combustion flue gas through the exhaust heat recovery device, from the heat exchanger and configured to perform indirect heat exchange between the combustion flue gas and the primary compressed air and supply water, the saturator being configured to permit steam to be entrained in the primary compressed air, wherein the saturator includes a supply water header configured to introduce the supply water into the saturator, a plurality of heat exchange tubes configured to communicate with the supply water header at a first end of the saturator and which are arranged within the saturator, a storage header configured to communicate with the plurality of heat exchange tubes at a second end of the saturator, the storage header having an introducing part configured to introduce the primary compressed air into a space in the storage header for storing the supply water, the saturator further including a supply water circulation line by which the supply water is circulated through the saturator, wherein the saturator is configured to pass the primary compressed air through spaces within the plurality of the heat exchange tubes through which the supply water circulates in the shape of a wet wall along inner wall surfaces of the plurality of heat exchange tubes, the saturator is further configured to perform heat exchange with the combustion flue gas flowing against outer peripheries of the plurality of heat exchange tubes to generate steam from the supply water, and the saturator being configured to permit the generated steam to be entrained in the primary compressed air flowing through the saturator,
wherein the system is configured to first introduce the primary compressed air to the saturator in which the steam is entrained by the primary compressed air and compress the primary compressed air to produce the secondary compressed air in the secondary air compressor, then heat the secondary compressed air in the heat exchanger, and then introduce the heated secondary compressed air into the combustor, the method comprising:
subjecting the combustion flue gas from the gas turbine to heat exchange with the secondary compressed air in the heat exchanger of the exhaust heat recovery device;
recovering heat from the combustion flue gas via heat exchange between the combustion flue gas and the primary compressed air in the saturator after subjecting the combustion flue gas to heat exchange with the secondary compressed air in the heat exchanger;
introducing the primary compressed air from the saturator into the secondary air compressor, thereby producing the secondary compressed air, then recovering heat from the combustion flue gas via heat exchange with the secondary compressed air in the heat exchanger, thereby heating the secondary compressed air; and
introducing the heated secondary compressed air into the combustor to combust fuel.

### Claim 2

A system comprising:
a gas turbine having a combustor configured to combust fuel with compressed air and a power turbine configured to be driven by combustion flue gas from the combustor; and
an exhaust heat recovery device configured to receive the combustion flue gas from the power turbine and recover heat energy from the combustion flue gas,
wherein the gas turbine comprises a primary air compressor and a secondary air compressor, the primary air compressor configured to compress air to produce primary compressed air, the secondary air compressor configured to compress the primary compressed air to produce secondary compressed air, wherein the compressed air includes the primary compressed air and the secondary compressed air,
wherein the exhaust heat recovery device includes:
a heat exchanger configured to perform indirect heat exchange between the combustion flue gas and the secondary compressed air, and
a saturator provided downstream, with respect to a flow of the combustion flue gas through the exhaust heat recovery device, from the heat exchanger and configured to perform indirect heat exchange between the combustion flue gas and the primary compressed air and supply water, the saturator being configured to permit steam to be entrained in the primary compressed air,
wherein the saturator includes:
a supply water header configured to introduce the supply water into the saturator,
a plurality of heat exchange tubes configured to communicate with the supply water header at a first end of the saturator, the plurality of heat exchange tubes being arranged within the saturator,
a storage header configured to communicate with the plurality of heat exchange tubes at a second end of the saturator, the storage header having an introducing part configured to introduce the primary compressed air into a space in the storage header for storing the supply water, and
a supply water circulation line via which the supply water is circulated through the saturator,
wherein the saturator is configured to pass the primary compressed air through spaces within the plurality of the heat exchange tubes through which the supply water circulates in the shape of a wet wall along inner wall surfaces of the plurality of heat exchange tubes, is configured to perform heat exchange with the combustion flue gas flowing against outer peripheries of the plurality of heat exchange tubes to generate steam from the supply water, and is configured to permit the generated steam to be entrained in the primary compressed air flowing through the saturator; and
wherein the system is configured to first introduce the primary compressed air to the saturator in which the steam is entrained by the primary compressed air and compress the primary compressed air to produce the secondary compressed air in the secondary air compressor, then heat the secondary compressed air in the heat exchanger, and then introduce the heated secondary compressed air into the combustor.

### Claim 3 (depends on 2)

The system according to claim 2, further comprising:
a cooling tower configured to cool the combustion flue gas discharged from the exhaust heat recovery device; and
a supply water supply line configured to supply condensed water as the supply water to the supply water circulation line.

### Claim 4 (depends on 3)

The system according to claim 3, wherein the heat exchanger is a first heat exchanger and wherein the exhaust heat recovery device further includes an additional heat exchanger downstream, with respect to the flow of combustion flue gas through the exhaust heat recovery device, from the first heat exchanger and the saturator, the additional heat exchanger configured to perform indirect heat exchange between the combustion flue gas and the supply water in the supply water supply line.

### Claim 5 (depends on 3)

The system according to claim 3, comprising:
a CO2 recovery apparatus that recovers CO2 in the combustion flue gas from the cooling tower.

### Claim 6 (depends on 5)

The system according to claim 5, wherein the CO2 recovery apparatus includes a CO2 absorption tower configured to absorb CO2 from the combustion flue gas with an absorbing liquid, and an absorbing liquid regeneration tower configured to regenerate the absorbing liquid which has absorbed CO2, wherein the absorbing liquid is circulated and reused.